Now to connect the external panel and batteries and such. The terminal blocks are OK but not very elegant. Instead, I will use pluggable connectors. Audio connectors will work well here and I only need 2 pins (ground and signal) per connection so mono 3.5mm headphone plugs and jacks are an inexpensive an easy-to-get solution. Be sure to get panel-mount jacks!

Start with the JST cable that goes to the charger output (to measure the lipo). Unscrew the plug, slip thru the wire, Then solder each pin to crimpies. As a rule, you should always make 'sleeve' or 'ring' ground and 'tip' positive signal. Keeps things easy to track!

Crimp, making sure not to short the wires. This can be a bit challenging so use a multimeter to test!

Next, the miniB usb cable is stripped and the red and black wires pulled out. We also use some heatshrink to protect the end of the cable.

Crimp

Heat shrink!

Next, the jacks. Connect any stranded wire to the sleeve and tip connections as shown.

We like heat shrink!

Connect the jacks to the terminal blocks.

Now is a good time to test, before finishing it all up! Verify you're getting reasonable voltages from the panel and lipoly battery. If you can get near a window, see if you can get the battery charging.